A volatile compound such as aromatic and essential oil has been released in a controlled manner by mixing the volatile compound with an ethylene-vinyl acetate resin and the like, enclosing same in cyclodextrin, mixing same with a naturally occurring shellac resin, and other method.
However, the conventional methods are associated with problems in that, due to the high melting point of synthetic resin such as ethylene-vinyl acetate resin, a volatile compound is volatilized when being mixed with the synthetic resin to reduce its yield, and that the volatile compound considerably softens the produced composition as a result of its plasticizing effect, thereby decreasing sustained release by the synthetic resin. While cyclodextrin may be used, cyclodextrin itself is costly, and does not permit easy control of release rate, since the volatile compound is not released unless placed in a certain range of humidity, whereas rapidly released in too high a humidity.
In the meantime, a naturally occurring shellac resin is superior in safety and control of release rate, whereas the release property thereof changes rather easily according to humidity. When it is heat-melted to be mixed with a volatile compound, it tends to be thermoset to degrade workability during production or processability of the obtained mixed composition.
As the situation stands, there has been a great demand for a controlled release composition containing a volatile compound, which composition being superior in the controlled release of the volatile compound, particularly controlled release of the volatile compound in a limited space or indoors or in an open space, and free of problems of a varying release rate due to humidity and thermosetting during production process.